As a mobile phone system, for example, a GSM system which is called “the second generation mobile phone system” is put into practical use. The standard thereof is Digital cellular telecommunications system (Phase 2+); Radio transmission and reception (Release 1999), GSM 05. 05 version 8.15.0 (2003-04) of ESTI (URL: www.etsi.org/getastandard/home.htm).
In this system, mobile phone services started with 900 MHz band, and thereafter, 1800 MHz band and 1900 MHz band became available along with the increase in the number of subscribers. Consequently, the so-called multi-band mobile phone corresponding to a total of 3 bands have been in widespread use.
Thus, along with the increase in the number of frequency bands, the number of RF components such as an RF filter and a low noise amplifier has been increasing. However, since a demand for size and weight reduction to a mobile phone has been increasing, the RF unit must be reduced in size. In addition, the mobile phone must be realized at low cost by suppressing components cost against increase in the number of RF components.
Further, in WCDMA system which is the third generation mobile phone system, services also started with 2.1 GHz band. The standard for the system is Technical Specification Group Radio Access Networks; UE Radio Transmission and Reception (FDD) (Release 6), 3GPP TS 25.101 v6.5.0 (2004-09) of 3GPP (URL: www.3gpp.org/specs/specs.htm).
For the application to the WCDMA system, the mobile phone must be of a dual system having both of an RF transceiver for GSM system and an RF transceiver for WCDMA system, where the number of frequency bands is 4 in total.
In the third generation mobile phone system, functions for still image transmission, moving image transmission, a memory interface and the like are required in the mobile phone, and thus, the number of components such as an image pickup device, a plurality of liquid crystal displays, a moving image coding/decoding IC, an image memory, an IC card slot and the like increases. As a result, the demand for size reduction of the RF transceiver becomes more severe.
For realizing such a multi-band or multi-system mobile phone, the so-called RF module which is a part in which RF units are integrated is used.
A conventional example of such an RF module is described in Japanese Patent Application Laid-open Publication No. 2004-95633 (Patent Document 1), for example, in which a SAW filter (surface acoustic wave filter) used in a mobile phone and an RF LSI are mounted on the same printed circuit board and resin-sealed to form a module. In this conventional example, electrical connection between a SAW terminal and the printed circuit board and electrical connection between the RF LSI and the printed circuit board are made by means of the wire bonding.
A conventional example of the SAW filter is described in Japanese Patent Application Laid-Open Publication No. 2004-215218 (Patent Document 2), which shows a SAW filter with a so-called flip-chip configuration in which electrodes provided on a piezoelectric substrate are directed toward a printed circuit board and then mounted.
This type of filter is also called CSP (chip size package) filter. In the conventional example, since wire bonding is not utilized for the connection between the SAW terminal and the filter printed circuit board, a component area can be close to a SAW chip area, and thus, the size reduction can be achieved.
In the Patent Documents 1 and 2, however, there is not any description about an optimal technology for modularizing the SAW filter of the CSP together with the RF LSI.
As one example of RF filters used in mobile phones, a FBAR (Film Bulk Acoustic Resonator) is described in, for example, Japanese Patent Application Laid-Open Publication No. 2004-222244 (Patent Document 3).
In the Patent Document 3, however, there is not any detailed and specific technology for realizing a module in which the FBAR and the RF LSI are mounted together.